Obesity is a significant physical and mental health problem for millions of Americans. While behavioral weight loss programs have shown promise, the amount of weight lost during such programs is often clinically insignificant. Furthermore, obese individuals rarely lose additional weight after such treatments. These results suggest that altering eating habits - the goal of most behavioral programs - may be insufficient to produce meaningful weight losses in the obese. Little attention has been paid to the identification of factors which predipose obese individuals to overeat. The purpose of the proposed projects is to investigate the role of two such factors: emotional eating and a low level of reinforcement for activities other than eating. The first study will test the prediction that obese students engage in emotional eating more often than normal weight students. Participants will be asked to continuously self-monitor their emotions and food intake for 12 days. Participants will be told we are studying the effects of food additives on mood. The second study will test two predictions: that normal weight students receive higher levels of nonfood-related reinforcement than obese students and that level of reinforcement and caloric intake are inversely related for obese, but not for normal weight students. Fifty normal weight and 50 obese students will complete a measure of the number of pleasant activities experienced during the previous month. In order to conduct a more refined analysis of the relationship between reinforcement level and caloric intake, 15 individuals from each group will then be randomly selected and asked to monitor continuously their food intake and pleasant activities for 24 days. A cover story involving the relationship between food additives and energy level will be used in Study II. In Study III, obese community residents who join our Weight Loss Clinic will complete a measure of reinforcement level and will self-monitor their emotions and caloric intake for a week before the clinic begins. These data will be used a) to evaluate hypotheses tested in Studies I and II with a clinically relevant population, and b) to evaluate emotional eating and reinforcement level as short- and long-term predictors of success at weight reduction and as potential treatment targets in comphrehensive weight-loss treatment programs.